The object of the present invention is a composition, containing aromatic enamines and carbonyl compounds, for dyeing fibers, particularly keratin fibers (such as human hair), a method for dyeing fibers, especially keratin fibers, a multi-component kit for dyeing and, later on, decolorizing fibers, particularly human hair, which kit contains a composition for producing a dyeing of the fibers as well as a composition for the reductive removal of the dyeing, as well as a method for dyeing and later on decolorizing fibers, particularly keratin fibers.
Hair dyeing compositions are divided mainly into the area of oxidation dyes and that of tinting, depending on the initial color of the hair that is to be dyed and on the end result desired. Oxidizing hair dyes are outstandingly suitable for covering larger portions of gray. Oxidizing dyeing agents, which are used when the gray portion does not exceed 50%, generally are referred to as oxidative tints, whereas the oxidizing dyeing agent, used when the gray portion exceeds 50% or for “brighter dyeing”, usually are referred to as oxidative dyes. Direct dyes are contained mainly in non-oxidizing dyes (so-called tinting agents). Direct dyes are contained mainly in non-oxidative dyeing agents (so-called tinting agents). Because of their small size, some direct dyes, such as the nitro dyes, can penetrate into the hair and dye it directly, at least in the outer regions. Such tints treat the hair very gently and usually withstand 6 to 8 washings and enable gray to be covered to about 20% to be covered.
In general, direct and oxidative tints are washed out of the hair after a few washings. The time period depends very much on such factors as the structure of the hair and on the shade used. Oxidative dyes can partly fade with time, but usually remain in the hair until it is cut the next time. However, removal of the hair dyeing at any time may be desirable if a particular color is to be worn only for a certain time or if the user is not satisfied with the dyeing. Likewise, when hair dyeing is used for the first time, the possibility of removing the dyeing gently and completely reduces the fear of too drastic a color change (“dyeing as a test”).
The German Offenlegungsschrift 197 45 292 discloses the use of a combination of malonaldehyde derivatives, such as malonaldehyde bis-dialkyl acetals, and amines or compounds with an acidic CH group for dyeing hair without the use of oxidizing agents. Likewise, it is known from the state of the art, for example, from K. H. Schrader, “Grundlagen und Rezepturen der Kosmetika (Fundamentals and formulations of cosmetics)”, 2nd edition (1989), pages 807 and 808, that so-called stripping agents, which contain active reducing or oxidizing agents, can be used for removal of unsuccessful dyeings. However, such stripping agents cause considerably damage to the hair and remove the dye completely only in rare cases.